Hot water services include systems that provide hot water to water use fixtures, such as faucets, showers and other fixtures. Such systems typically include a water heater that receives a supply of cold water and heats the water to a set temperature. It is often desirable to heat the water in the water heater to a set temperature that is greater than the desired temperature of the water delivered to the fixtures. In this situation, the system typically utilizes a thermostatic or other type of mixing valve that operates to mix a flow of hot water from the water heater with a flow of cold water such that the delivered hot water is at the desired temperature. This has the benefit of providing a larger volume of hot water than that stored in the water heater.
In the event of a failure of the mixing valve to properly meter cold water into the flow of hot water from the water heater, the temperature of the discharged hot water flow from the mixing valve can diverge from the desired water temperature. When an insufficient amount of cold water is metered into the flow of hot water from the water heater, the discharged hot water from the mixing valve will exceed the desired water discharge temperature and could potentially result in a scald injury. In the event that the mixing valve meters more cold water into the flow of hot water from the water heater than is necessary, the discharged flow of hot water will have a temperature that is below the desired discharge temperature.